I am encountering the same issue, also running ArcGIS 10.1 and Oracle 11g, when trying to join a feature class and a table in ArcMap:
If both the feature class and the table are NOT registered as versioned, then the join does works without error.
If either the feature class, or the table, or both of them are registered as versioned, then the join will fail.
Has anyone found a solution to this problem? There is surprisingly little documentation of this bug on the web - is anyone else experiencing the same issue?